Question

there are 1800 gym members in total. 3/4 are aged 25-59, 1/5 are over 60 and the remainder are under 25 years. how many members are under 25?

Answer 1

I could be wrong. Just saying.
1800*3/4=1,350
1800*1/5=360
1,350+360=1,710
1,800-1,710=90

I'm not an expert.